Carton end closure



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CARTON END CLOSURE Filed Oct. '13. 1949 5 Sheets-Sheet 5 United States Patent CARTON END CLOSURE Isaac L. Wilcox, Fulton, N. Y., assignor to Oswego Falls Corporation, Fulton, N. Y., a corporation of New York Application October 13, 1949, Serial No. 121,085

2 Claims. (Cl. 2295.5)

This invention relates to end closure structures for car- 7 tons, and more particularly to an end closure structure for liquid tight cartons having bodies rectangular in cross sectional form, the end closure being formed from a fiat blank of sheet material with a flange encircling the body of the carton and being afiixed thereto by an adhesive substance.

Up until now, cartons have not been successfully made for liquid products with an end closure structure of the type above referred to. The reason why such cartons were not successful is because the excess material at the corner portions of the flange of the end closure contiguous to the corners of the carton body could not be formed accurately about the corners of the body and engage the same in a smooth, wrinkle-free contact, and the excess material not immediately contiguous to the carton body could not be arranged in such a manner that it would maintain its initially formed shape, but had a tendency to loosen and move away from the corner of the carton. These defects resulted in leaky cartons.

This invention has as an object an end closure structure for liquid tight cartons embodying a novel arrangement of the excess material in the corner portions of the end closure flange, whereby the flange is drawn smoothly and uniformly throughout its width about the corners of the carton body, and the excess material so compacted into a rigid mass that it will not open up, or become disengaged from the carton corners.

The invention has as a further object a novel method for forming and applying end closures to cartons of the type referred to.

The invention consists in the novel features and in the combinations and constructions hereinafter set forth and claimed.

In describing this invention, reference is had to the accompanying drawings in which like characters designate corresponding parts in all the views.

In the drawings- Figure 1 is a perspective view of a carton provided with an end closure embodying my invention.

Figure 2 is a plan view of the end closure blank.

Figure 3 is a vertical sectional view of a portion of the carton body mounted upon a mandrel, the flat body blank positioned above the carton and the forming die and sealing jaws positioned above the blank.

Figure 4 is a view, similar to Figure 3, with the forming die moved downwardly into engagement with the marginal portion of the blank.

Figure 5 is a view, similar to Figures 3 and 4, showing the forming die moved farther downwardly and the marginal portion of the blank folded at a sharper angle.

Figure 6 is an enlarged horizontal sectional view through the mandrel and carton taken on a line corresponding to line 6-6, Figure 5.

Figure 7 is an enlarged fragmentary sectional view corresponding to the upper left portion of Figure 5.

Figure 8 is a view of the structure shown in Figure 7 taken on line 88, Figure 7.

Figure 9 is a view corresponding to Figure 7 showing the forming die moved further downwardly.

Figure 10 is a view similar to Figure 8 taken on line 1010, Figure 9.

Figure 11 is a view similar to Figures 7 and 9 showing the forming die moved downwardly out of engagement with the flange of the closure.

Figure 12 is a view taken on line 1212, Figure 11.

Figure 13 illustrates the completion of the downward 2,704,179 Patented Mar. 15 1955 movement of the die and sealing jaws and with the sealing jaws moved against the flange of the closure and pressed into sealing engagement with the carton.

Figure 14 is a view taken on line 1414, F gure 13.

Figure 15 is a top plan view of the sealing aws and their arrangement in relation to the carton.

Figure 16 is an enlarged bottom plan view of the forming die plate.

Figures 17 and 18 are views similar to Figure 14 showing slightly different formations of the excess material in the corner positions of the closure flange.

The rectangular carton body 20 is of conventional formation having a side wall seam 21. The end closure, shown at the bottom of the carton in Figure l, is formed with a flange 22 encircling the carton body. The end closure is formed from a flat blank of sheet material having a central portion 23 closing the end of the carton. The blank is provided with score lines 24 commensurate with the dimensions of the body 20 and which define a marginal portion 25 which is bent, or folded, to form the flange 22. The blank, shown in Figure 2, is formed with notched corners, as at 26.

In the application of the end closure to the carton, the carton is positioned on a rigid mandrel 27 with the end of the carton body substantially flush with the end of the mandrel. The flat end closure blank is positioned over the end of the carton, as shown in Figure 3, and the marginal portion 25 is folded downwardly toward the side walls of the body 20. This folding operation is accomplished by a die plate 30 illustrated in Figure 16. The die plate is formed with a central rectangular opening 31 slightly larger than the carton body 20. The under side of the die plate, adjacent the opening 31, is beveled as at 32, and the corners of the opening 31 are formed with diagonally extending concavities 33, the bottom wall of which inclines upwardly and inwardly, as at 34, see Figures 7, 9 and 11.

The die plate 30 is moved downwardly and the marginal portion of the plate about the opening 31 engages the marginal portion of the flange, bending or folding it downwardly, see Figure 4. During the downward movement of the die plate and associated structure, the central portion 23 of the blank is clamped firmly against the end of the mandrel 27 by a presser foot omitted from the drawings in order to better show the jaw structure for applying heat and pressure to the closure flange. As the die plate 30 is moved downwardly, the marginal portion 25 of the blank is progressively folded at a sharper angle.

In the form shown in the drawings, the carton body 20 is formed of sheet fibrous material, such as paperboard, and the end closure blank is formed of similar material. The under or inner side of the end closure blank is coated with a thermoplastic material, as indicated at 40, and preferably the outer surface of the body 20 is likewise coated with the same, or a similar material. Where the carton is likely to be subjected to excessive moisture, a coat of thermosetting material 42 may be applied to the outer surface of the end closure.

As the die plate 30 moves downwardly, the excess material at the corner portions of the end closure flange is formed into an open fold or loop 43 extending diagonally from the corners of the carton. This fold is formed by the concavities 33 formed in the corners of the opening 31 in the die plate. Due to the inclination 34 of these concavities, the sides of the fold contiguous to the corner of the carton, as indicated at 45, are contracted and drawn about the body corners and in this operation, the sides of the fold are formed with corrugations 46, see Figure 10. As the die plate 30 continues its downward movement, the portions 45 are progressively contracted, the corrugations 46 enlarged, and the diagonally extending length of the fold 43 reduced. The area of the excess material at the corners of the flange is illustrated in Figure 12 at the time the die plate 30 has been moved downwardly past the bottom edge of the flange.

At this stage of the end closure formation, it will be observed that the portions 45 of the flange have been drawn in close proximity to the corners of the carton and that the corrugations in the sides of the fold are arranged uniformly and developed to a considerable extent.

With the die plate 30 positioned as shown in Figures 11 and 12, the flange is pressed against the carton body 20, which is backed up by the rigid metal mandrel 27, as previously stated. This pressure is applied by heated jaws 48, 49, 50 and 51 which are movable diagonally toward the center of the carton. These jaws are arranged immediately above the die plate 30 and the ends of the jaws confronting the carton or closure flange are formed with V shaped notches, the sides of which extend from each corner of the closure flange an appreciable distance toward the adjacent corners of the flange. The jaws 48, 50 are formed with notches at the ends of the V face to slidably receive corresponding tongue portions 52 formed on the jaws 49, 51, the arrangement being such that the faces of the jaws contracting the flange overlap at the central portion of each side of the flange.

Figures 3, 4, and 13 are taken through the overlapping portions of the jaws. The faces of the V formation in the jaws are preferably relieved to form parallel spaced apart ridges 55, the purpose of which is to concentrate pressure exerted by the jaws on the closure flange to restricted areas and accordingly, at those areas exerted a higher pressure on the flange.

The die plate 30 and the jaws may be arranged in a forming and applying head structure which includes suitable means for applying heat to the jaws and actuating mechanism for moving the jaws diagonally inwardly when they are positioned as illustrated in Figures 11 and 12. Such a head structure and supporting structure for the mandrel 27 is disclosed in detail in the co-pending application of Barnes et al., Ser. No. 99,818, filed June 17, 1949.

As the heated jaws 48, 49, 50, 51 are moved inwardly under a high pressure, the flange of the end closure is pressed into sealing engagement with the side walls of the body 20, and the excess material in the fold 43 is compacted into a hard rigid mass, as shown in Figure 14. Previous to the movement of the jaws, the sides of the fold at the base thereof have been drawn smoothly about the corners of the carton, as previously stated, and the fold has been moved inwardly with a corrugation formed in each side of the fold. Accordingly, when the jaws move in diagonallv under high pressure, those portions of the flange contiguous to the corners of the carton are pressed tightly into sealing engagement with the corners of the carton and are free from wrinkles, corrugations and any unevenness, and the remainder of the excess material in the fold is compressed uniformly with the thermoplastic material 40 extending into the compacted mass, as illustrated in Figure 14. In other words, due to the progressive formation of the loop, as illustrated in Figures and 12, the material in the fold or loop compacts in most instances into the uniform arrangement shown in Figure 14. However, due to the variations in the paper of the closure blank due to atmospheric changes in humidity etc., the material in the fold may compact in the forms shown in Figures 17 and 18 but, in any event, that portion of the flange contiguous to the corners of the body is always drawn smoothly about the body corners to form a perfect liquid tight seal with the body corners, and the outer material in the fold compacted in a more or less uniform manner with the coating 40 extending into the compacted mass.

It will be noted, in Figures 14, 17 and 18, that the radius at the bottom of the V formation in the views, as indicated at 60, is substantially less than the radius on the corners of the mandrel 27, as indicated at 61. This arrangement is to provide an area or space radially greater than the distance between the sides of the jaw faces and the sides of the mandrel to accommodate the excess material at the corners of the flange. However, this space is so controlled relative to the thickness of the side wall and the thickness of the end closure blank as to exert a sufliciently high pressure on the excess material to compact it into a hard rigid mass.

The progressive formation of the fold 43 providing the corrugations 46 in the side thereof is important in effecting to the proper extent a folding or overlapping of the material in the fold rather than permitting it to take whatever course it might with the natural tendency to wad up. This is important so that the jaws may move inwardly sufliciently not only to apply the compacting pressure on the excess material, but to also apply proper sealing pressure on the flange intermediate the corners of the carton.

With this method, end closures formed of paperboard may be so formed and applied in perfect liquid tight relation without the necessity of impregnating the end closure blank with wax. 'Heretofore, parts formed of relatively thick paperboard in the order of .020 of an inch, or more, have not been successfully subjected to drastic forming operations without first having been heavily impregnated with wax. In the formation of end closures for fibrous cartons, wax impregnated parts do not form liquid tight sea s.

What I claim is:

1. An end closure structure for cartons formed of deformable sheet material having a tubular body polygonal in cross section with the outer corner surfaces being rounded and smooth, an end closure having a flat central portion positioned at the end edge of the body and a marginal portion folded perpendicular to said central portion and forming a continuous flange encircling the body and sealed thereto by adhesive, the inner surface of the corner portions of said flange engaging the outer corner surfaces of the body being smooth and free from wrinkles, and the excess material at said corner portions of the flange being formed in overlapping folds positioned exteriorly of the flange and compacted into a rigid mass.

2. An end closure for cartons formed of sheet material having a tubular body rectangular in cross section with the outer corner surfaces being rounded and smooth, an end closure having a fiat central portion positioned at the end edge of the body and a marginal portion folded to form a continuous flange encircling the body, the side of said closure confronting the body being coated with a thermoplastic adhesive, the inner surface of the corner portions of said flange engaging the outer corner surfaces of the body being smooth and free from wrinkles, the excess material at the corner portions of the flange being formed into overlapping folds positioned exteriorly of the flange and compacted into a rigid mass of the same thickness as the flange, the entire area of said flange engaging the body being permanently sealed thereto and saiilcll folds being sealed together'by said thermoplastic a esrve.

References Cited in the file of this patent UNITED STATES PATENTS 

